GeNED.ar cohort: Neuroimaging resource for aging studies in an admixed population from Argentina.

Well-characterized cohorts are essential for advancing neuroimaging biomarkers and refining models of brain aging and dementia across diverse populations. Despite growing neuroimaging research in Latin America, additional multimodal cohorts integrating imaging, genomic, and environmental data are needed to capture population diversity. We present GeNED.ar (Genetics and Neuroimaging of Aging and Dementia in Argentina), a multimodal cohort established in the Metropolitan Area of Buenos Aires to investigate brain aging in a population with genetic admixture and socioeconomic heterogeneity. The dataset combines two complementary recruitment strategies, community-based healthy participants and Memory Clinic attendees, including 3T MRI, genome-wide genotyping, and detailed sociodemographic data from 367 individuals aged 18-94 years. Participants comprise healthy individuals (n = 235) and Memory Clinic attendees classified as cognitively unimpaired (n = 65), mild cognitive impairment (n = 37), Alzheimer's or mixed dementia (n = 24), and vascular dementia (n = 6). Genetic ancestry analysis (n = 191) indicated a predominantly admixed population (65% European, 28.3% Native American) with significant differences across recruitment sources. Brain age gap (BAG), estimated from T1-weighted MRI, increased progressively along the clinical continuum, where people with dementia exhibited older-appearing brains relative to cognitively unimpaired participants, and intermediate values were observed in mild cognitive impairment. No independent associations were observed between BAG and individual genetic or environmental risk factors. By integrating multimodal MRI and genomic data across complementary recruitment settings, GeNED.ar provides a unique regional resource to evaluate neuroimaging biomarkers, facilitate cross-cohort validation, and strengthen the generalizability of aging and dementia models in genetically and socially diverse populations.